Film forming machine



15, 1935. c. E. HETZEL 2,017,094

FILM FORMING MACHINE Original Filed Sept. 24, 1926 1 fi ii I I T1 F I] 1- 1| u n [I l I I II I I II II II H H H II I v i I H I H II [I N M H H H ll H n 1 u k I I I I I .C M \l I.

r Maw ATTORNEYfi Patented Oct. 15, 1935 lTED STATES animal PATENT OFFICE FILM FORMING MACHINE Charles E. Hetzel, South Hadley Falls, Mass,

assignor to Zeloid Products-Corporation, Holyoke, Mass., a, corporation of Delaware Substitute for abandoned application Serial No. 137,462, September 24, 1926. This application May 15, 1931, Serial No. 53 'l,591 Y 1 Claim.

of a ccagulum of dissolved cellulose.

Another object of my invention is to provide a machine having a coating belt, means for coating a solution of cellulosic material thereon, means for coagulating the cellulose to form a homogeneous cellulosic sheet, and means for cleaning the coating belt preparatory to recoating with more cellulosic solution.

In the prior art of the preparation of transparent homogeneous films of cellulosic material, it has been customary to dissolve the cellulose, as by the well-known Viscose process, and then to extrude the viscous solution of cellulose into a bath of dissolved coagulant to forma thread or a sheet. The material was then'processe'd, by treatment in other materials, for further coagulation and purification. Diificulty was, however, experienced in the extrusion of the dissolved cellulose, and in the handling of the sheeted cellulose material in the first coagulating bath. The material is very fragile immediately after the extrusion process, and surface'tension effects and similar forces tend to interfere with the production of a smooth, unwrinkled, sheet of uniform thickness. Likewise much difliculty is encountered in the conveying of the sheet from the first coagulating bath to other, successive, treating baths.

My invention hereinafter described in this application, which is a substitute for my former application 137,462 filed September 24, 1926, provides means whereby the cellulosic material is coated upon a belt which provides additional strength and support for the very fragile sheet, until the coagulation has proceeded to an extent such that the sheet has sufi'icient strength for reasonable handling and transfer to the final coagulating and purifying processes.

By this means I am enabled to produce a much smoother, more uniform, and much stronger sheet of cellulosic material, and I am enabled to remove many of the difficulties of handling, and to avoid much of the delicate care previously necessary.

Other objects and structural details of my invention will be apparent from the following description when read in connection with the accompanying drawing, wherein:

Fig. 1 is a diagrammatic representation in vertical side view of an embodiment of the apparatus of my invention;

Fig. 2 is a vertical front'view of the same embodiment;

r ;Fig. 3 is a broken away View of the rollers under 5 the coagulatir'igi'section of the device, and

Fig. 4 is a perspective view of a broken fragment of the rollers, belt and coagulum of the device.

or it "may be of a non-metallic material such as rubber. The belt is carried and traversed by a plurality of rolls 2, 3, 4,;5, 6 and l as indicated, which keep it under moderate tension.

" Provisionis made for applying to the belt a 20 coating of the cellulose solution. The provision may" consist ofa coating roll 8 as shown bearing against the-outer surface of the belt, which is supplied with the cellulose solution by an additional roll 9, rotating in a tank H of cellulosic 25 solution as indicated. Or alternatively the lower arc of the roller 2, may be adapted to dip into a bath of the cellulose solution, or other wellknown means may be provided for the application of a coating of the cellulose solution to the 30 belt, according to the thickness of coating required. The belt is carried upward from the coating device for a distance, chosen according to the thickness of coating desired. In the course of the upward travel, excess material drains down- 35 ward and off at a speed depending upon the rate of travel of the belt and the viscosity of the solution. Likewise any air bubbles in the solution come to the surface and burst, and surface tension forces smooth out any differences in thickness 40 which might exist in the coating as it leaves the coating device. During the upward travel also the solution stiffens, and sets slightly or jels and by the time it has reached the end of the upward travel, part, or all, of its fluidity has been 45 lost.

At the end of the vertical travel the belt is drawn over a top roll 4, and through a period of horizontal travel to another top roll 5. During this period of horizontal travel, the surface ten- 50 sion forces complete the smoothing out of the coating and cause it to become of a very uniform thickness. The coated sheet is then drawn over the roll 5, in a line of travel along a downward slope.

nary coagulation of the coating while it'is still on the belt.

Rolls I5 are provided for supporting the during this downward sloping travel. .fI'hese rolls are desirably made with enlarged ends, that is, with the diameter substantially greater :for a short distance from the ends asshown-inFigsB and 4. They serve to raise the edgesof "-thebelt above the center portion and therebypmventthe coagulating solution fromrunning-overthe sides and onto the back of the belt. In order that an undue strain may not be put upon therbelt, it is desirable that either the top roll 5 orthe following roll 6 be slightly-ridllcddzimdiameterxat.its

ends.

After the application of the .coagnlatingysolution and a period of downward travel, the .belt is drawn around anotherroller .6. mheapplication of the coagulant tends to-destroythe adhesion between the coating andthleebelt, and during the period of downward travel sufficient-coagulation occurs, not only to free the sheet from-the i-coating belt but to develop a substantial strength in the cellulosic coating itself. .Thetcoated sheet is thus readily removable fromthe coating beltand such removal is therefore eficted-atorbeforethe.

material reaches @the .roll 6 the :action' .of the feed rollers-:Ga of a vat 6b. The beltbeing-drawn around theroll -6 readily releases thefpartially co- ,agulated coating. The coated sheet-isthen drawn into the sequence of vats for the .complete reoagulationand purification of the sheet.

.After'being drawn-aroundthe roller-6 zthe-coatleave the belt in clean condition for re-coating. The cleaning rolls may be arranged in a single series as shown, or they may be broken up into several series, by an additional tensioning roll,

which may, if desired, be mounted upon guides 5 I Ting rolls to the bottom roll I after which it may be 10 re-coated, and returned through the previously described cycle.

' The operation of my device thus allows full :play to the surface tension forces and makes optimum utilization of them for the production of a smooth, unwrinkled sheet of material of uni- :formthickness. ,It likewise allows convenient application of the coagulating solution, and permits the delivery of a sheet of partially coagulated material which is of substantial strength and adapted :to easy handling through the following and finishing processes. I

By the apparatus of my invention I am thus enabled to produce a sheet of cellulosic material, of superior strength, superior uniformity of thickness, and superior smoothness.

While-I have shown but a single embodiment of tiny invention in the accompanying description it is capable of various modifications therefrom without departing from the spirit thereof and it .is desired, therefore, that only such limitations shall be imposed thereon as are required by the prior art or indicated by the appended claim.

I claim:

' In combination, a coating carrying belt, processing means comprising means for the application of material thereto, and means for removing processed materials from said belt, means for minimizing the transfer of material to the 'back of said belt, means for cleaning the coating 40 surface of ,said belt and additional means for cleaning the back surface of said belt.

1 CHARLES E. HETZEL. 

